PROJECT SUMMARY: The overarching goal of our Training Program is to prepare MD, MD/PhD pediatricians, and PhD scientists for careers in independent research on topics relevant to digestive diseases in infancy, childhood, and adult life. The rationale for our program is founded upon the idea that meaningful and strong intellectual, mentoring, and financial support for newly emerging scientists will enable the recruitment of talented young people to our field, and foster early success in their long-term career development as effective independent investigators pursuing meaningful science relevant to health and disease of the alimentary tract. We offer training in 4 broad areas relevant to our field of gastroenterology: * Epithelial Cell and Molecular Biology - including Stem Cell/Developmental Biology and Enteric Neurobiology * Innate and Adaptive Mucosal Immunology; * Microbial Pathogenesis, Gut Microbiome, and effects on Metabolism; and * Clinical Research. The training program provides an in-depth comprehensive and strongly mentored scientific experience for each trainee in a research group at the forefront of its field. Eight postdoctoral positions are requested. 37 NIH-funded highly-accomplished core reseach faculty support this effort, providing great depth and diversity of scientific training and over $49 million in combined current research support. Opportunities for cross-fertilization among faculty members and their trainees are abundant. The Program Director is Dr. Wayne I. Lencer MD, Longwood Professor of Pediatrics, Harvard Medical School, and a widely respected investigator and mentor. Program steering committee includes Drs. Scott Snapper MD PhD, Rachel Rosen MD MPH and Jon Kagan PhD. An External Advisory Board and an additional invited outside reviewer provide oversight to the program. Scholarship Oversight Committees (SOCs) are assembled for each trainee to provide oversight (and further mentoring) in personal scientific and career development. Didactic course work is encouraged for both basic and clinical research training and supplemented with relevant seminars and journal clubs, a course in the responsible conduct of research, and an annual research retreat. For clinical research trainees, the program supports matriculation trough a Master?s Degree in Medical Science or Public Heath (MMSc or MPH) from Harvard Medical School or Harvard School of Public Health. Since 1997, 88% of our past 89 Trainees remain in academics, 6% in industry, 2% in government (NIH/FDA), and 2% are in clinical practice. 21% of our past Trainees have achieved independent research awards (RO1 or equivalent) and 62% have achieved additional career development awards (NIH K-series and F-series and equivalent). Our program has populated the faculty of academic institutions across the nation and internationally.